dianne feinstein, the democrat who chairs the senate intelligence committee, warned that shedding more light on who is being surveilled would you wo destroy the wire tapping program which she says has worked well. >> in four years, 100 arrests to prevent something from happening in the united states. some of which comes from this program. so i think it's a vital program. >> conservative analyst says a wide dragnet is worth the cost. >> let's suppose you're a pakistani, you don't have your green card, you call your uncle, yes, you could get caught up and maybe if he's a member of the taliban there's going to be somebody in the federal government who thinks we need to ask some questions of this person. >> but if you're the person here talking to the uncle and you're caught up in this -- >> you're not caught up in the sense that you're going to jail, in the sense that anything bad is going to happen to you. >> but there are concerns about that. civil libertarian julian sanchez points out that the national security agency which does most of this surveillance has a massive new data center i